Handheld tester for starting/charging systems

ABSTRACT

An improved hand held starting/charging system tester. According to one aspect of the present invention, the portable handheld tester includes a connector to which various test cables can be removably connected to the tester. Detection circuitry within the tester determines which of several types of test cable is connected to the tester before testing. According to another aspect of the present invention, the portable handheld tester includes an improved user interface that permits a user to review test data from previously performed tests and further permits a user to either skip a previously performed test (thereby retaining the previously collected data for that test) or re-do the test (thereby collecting new data for that test). According to yet another aspect of the present invention, the portable handheld tester that performs a more complete set of tests of the starting/charging system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to commonlyassigned, U.S. patent application Ser. No. 09/813,104 now U.S. Pat. No.6,570,385, filed on Mar. 19, 2001, which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field of electronictesting devices, and more specifically to a handheld device used to testthe starting/charging system of an internal combustion engine in avehicle.

BACKGROUND OF THE INVENTION

Internal combustion engines typically include a starting/charging systemthat typically includes a starter motor, a starter solenoid and/orrelay, an alternator having a regulator (or other charger), a battery,and associated wiring and connections. It is desirable to performdiagnostic tests on various elements of starting/charging systems todetermine whether they are functioning acceptably. It is typical duringmany such tests, e.g., starter tests, cranking tests, various regulatortests, etc., to adjust the operation of the vehicle while sitting in thedriver's seat e.g., starting the engine, turning lights and other loadson and off, revving the engine to a specific number of revolutions perminute, etc. Thus, it is desirable, if not necessary, to have one personsitting in the driver's seat during many starter/charger tests toperform the tests. For other tests, e.g., battery tests, the user neednot necessarily be in the driver's seat.

Testers used to test the starting/charging system of an internalcombustion engine are known. For example, the KAL EQUIP 2882 DigitalAnalyzer and KAL EQUIP 2888 Amp Probe could be used together to performa cranking system test, a charging system test, an alternator conditiontest, and an alternator output test. The KAL EQUIP 2882 Digital Analyzeris a handheld tester. Other known testers capable of testing astarting/charging system include the BEAR B.E.S.T. tester and the SUNVAT 40 tester, both of which allowed a user to test the starter,alternator, etc. Other testers capable of testing a starting/chargingsystem exist. The aforementioned BEAR B.E.S.T. and the SUN VAT 40testers are not handheld testers; they are typically stored and used ona cart that can be rolled around by a user.

Additionally, some other handheld testers capable of testing astarting/charging system are known. These devices typically have limiteduser input capability (e.g., a few buttons) and limited displaycapability (e.g., a two-line, 16 character display) commensurate withtheir relatively low cost with respect to larger units. The knownhandheld starting/charging system testers have several drawbacks. Forexample, the user interface on such devices is cumbersome. Additionally,some handheld starting/charging system testers have been sold witheither a shorter (e.g., three feet) cable or a longer (e.g., fifteenfeet) cable. With the shorter cable, two people would typically performthe tests of the starting/charging system, with one person under thehood with the tester and one person sitting in the driver's seat toadjust the operation of the vehicle. The longer cable would permit asingle user to sit in the driver's seat to perform the tests and adjustthe operation of the vehicle, but the user would need to wind up thefifteen feet of cable for storage. Lugging around the wound coils of thelong cable becomes especially inconvenient when the user wants to usethe tester for a quick battery check, because the wound coils of cablecan be larger than the test unit itself. Additionally, the userinterface in such units is typically very cumbersome.

There is a need, therefore, for an improved handheld tester capable oftesting a starting/charging system of an internal combustion engine.

SUMMARY OF THE INVENTION

The present invention is directed toward an improved hand heldstarting/charging system tester. According to one aspect of the presentinvention, the portable handheld tester comprises a connector to whichvarious cables can be removably connected to the tester. According toanother aspect of the present invention, the portable handheld testercomprises an improved user interface that permits a user to review testdata from previously performed tests and further permits a user toeither skip a previously performed test (thereby retaining thepreviously collected data for that test) or re-do the test (therebycollecting new data for that test). According to yet another aspect ofthe present invention, the portable handheld tester performs a morecomplete set of tests of the starting/charging system. For example, thehandheld portable tester preferably performs a starter test, threecharging tests, and a diode ripple test. According to still anotheraspect of the present invention, the portable handheld tester performsan improved starter test. More specifically to an implementation of thestarter test, the portable handheld tester performs a starter test inwhich the associated ignition has not been disabled, where a hardwaretrigger is used to detect a cranking state and then samples of crankingvoltage are taken until either a predetermined number of samples havebeen collected or the tester determines that the engine has started.

It is therefore an advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine having a connector to which a test cable can beremovably connected to the tester.

It is also an advantage of the present invention to provide a portablehandheld tester for a starting/charging system of an internal combustionengine that permits different test cables (e.g., the cables of FIGS. 5A,7A, and 8) to be used with a single tester, thereby allowing a widerrange of functions to be performed with the tester.

It is another advantage of the present invention to provide a portablehandheld tester for a starting/charging system of an internal combustionengine that permits an optional extender cable (e.g., the extender cableof cable of FIGS. 6A and 6B) to be used, thereby allowing the tester tobe used by one person sitting in a driver's seat for some tests, butallowing a shorter cable to be used for other tests.

It is a further advantage of this invention to provide a portablehandheld tester for a starting/charging system of an internal combustionengine that allows the tester to be stored separately from the cable.

It is yet another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that comprises an improved user interface.

It is still another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that comprises an improved user interface in which auser can review test data from previously performed tests and in whichthe user can, for each previously performed test, either skip thatpreviously performed test or re-do the test.

It is another advantage of the present invention to provide a portablehandheld tester for a starting/charging system of an internal combustionengine that comprises an improved user interface in which a user canreview test data from previously performed tests and in which the usercan, for each previously performed test, either retain the previouslycollected data for that test or collect new data for that test.

It is yet another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that performs a more complete set of tests of thestarting/charging system, preferably a starter test, three chargingtests, and a diode ripple test.

It is still another advantage of the present invention to provide aportable handheld tester for a starting/charging system of an internalcombustion engine that performs an improved starter test, preferably inwhich a hardware trigger is used to detect a cranking state and thensamples of cranking voltage are taken until either a predeterminednumber of samples have been collected or the tester determines that theengine has started.

These and other advantages of the present invention will become moreapparent from a detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which are incorporated in and constitute apart of this specification, embodiments of the invention areillustrated, which, together with a general description of the inventiongiven above, and the detailed description given below, serve to examplethe principles of this invention, wherein:

FIG. 1A is an isometric view of an embodiment of the starting/chargingsystem tester according to the present invention;

FIG. 1B is a high-level block diagram showing an embodiment of thestarting/charging system tester according to the present invention;

FIG. 2 is a medium-level block diagram showing a detection circuit and atest circuit of an embodiment of the starting/charging system testeraccording to the present invention;

FIG. 3A is a schematic block diagram showing more detail about oneimplementation of a detection circuit according to the presentinvention;

FIGS. 3B-3F are schematic diagrams showing equivalent circuits of aportion of the detection circuit of FIG. 3A showing the detectioncircuit of FIG. 3A in various use configurations;

FIG. 4A is a schematic block diagram showing more detail about oneimplementation of a voltmeter test circuit of the starting/chargingsystem tester according to the present invention;

FIG. 4B is a schematic block diagram showing more detail about oneimplementation of a diode ripple test circuit of the starting/chargingsystem tester according to the present invention;

FIG. 4C is a schematic diagram illustrating a test current generatorcircuit of the battery tester component of the present invention;

FIG. 4D is a schematic diagram illustrating the an AC voltageamplifier/converter circuit of the battery tester component of thepresent invention;

FIG. 5A shows a plan view of one implementation of a clamp cable for thestarting/charging system tester according to the present invention;

FIG. 5B shows a schematic diagram of connections within the clamp cableof FIG. 5A;

FIG. 5C shows a rear view of the inside of the housing of the clampcable of FIG. 5A;

FIG. 6A shows a plan view of one implementation of an extender cable forthe starting/charging system tester according to the present invention;

FIG. 6B shows a schematic diagram of connections within the extendercable of FIG. 6A;

FIG. 7A shows a plan view of one implementation of a probe cable for thestarting/charging system tester according to the present invention;

FIG. 7B shows a schematic diagram of connections within the probe cableof FIG. 7A;

FIG. 7C shows a rear view of the inside of the housing of the probecable of FIG. 7A;

FIG. 8 is a block diagram of a sensor cable, e.g., a current probe, forthe starting/charging system tester according to the present invention;

FIG. 9 is a high-level flow chart showing some of the operation of theembodiment of the starting/charging system tester of the presentinvention;

FIG. 10 is a medium-level flow chart/state diagram showing the operationof the test routine of the embodiment of the starting/charging systemtester of the present invention;

FIGS. 11A-11D are a low-level flow chart/state diagram showing theoperation of the test routine of the embodiment of the starting/chargingsystem tester of the present invention;

FIG. 12 is a low-level flow chart showing the operation of the startertest routine of an embodiment of the starting/charging system tester ofthe present invention; and

FIG. 13 shows a plurality of representations of screen displaysexemplifying an embodiment of a user interface according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1A and 1B, there is shown a handheld, portable tester10 according to the present invention for testing a starting/chargingsystem 11. The tester 10 comprises a handheld, portable enclosure 12housing an electronic circuit 14 that, among other things, tests thestarting/charging system 11. One or more user inputs 16, shown in FIG.1A as four momentary switches implemented as pushbuttons 18-21, allow auser to interface with the tester 10. A display 24, shown in FIG. 1A asa liquid crystal display (LCD) 26 having four lines of twenty characterseach, allows the tester 10 to display information to the user.

The tester 10 is placed in circuit communication with thestarting/charging system 11 via a cable 28. “Circuit communication” asused herein indicates a communicative relationship between devices.Direct electrical, electromagnetic, and optical connections and indirectelectrical, electromagnetic, and optical connections are examples ofcircuit communication. Two devices are in circuit communication if asignal from one is received by the other, regardless of whether thesignal is modified by some other device. For example, two devicesseparated by one or more of the following—amplifiers, filters,transformers, optoisolators, digital or analog buffers, analogintegrators, other electronic circuitry, fiber optic transceivers, oreven satellites—are in circuit communication if a signal from one iscommunicated to the other, even though the signal is modified by theintermediate device(s). As another example, an electromagnetic sensor isin circuit communication with a signal if it receives electromagneticradiation from the signal. As a final example, two devices not directlyconnected to each other, but both capable of interfacing with a thirddevice, e.g., a CPU, are in circuit communication. Also, as used herein,voltages and values representing digitized voltages are considered to beequivalent for the purposes of this application and thus the term“voltage” as used herein refers to either a signal, or a value in aprocessor representing a signal, or a value in a processor determinedfrom a value representing a signal. Additionally, the relationshipsbetween measured values and threshold values are not considered to benecessarily precise in the particular technology to which thisdisclosure relates. As an illustration, whether a measured voltage is“greater than” or “greater than or equal to” a particular thresholdvoltage is generally considered to be distinction without a differencein this area with respect to implementation of the tests herein.Accordingly, the relationship “greater than” as used herein shallencompass both “greater than” in the traditional sense and “greater thanor equal to.” Similarly, the relationship “less than” as used hereinshall encompass both “less than” in the traditional sense and “less thanor equal to.” Thus, with A being a lower value than B, the phrase“between A and B” as used herein shall mean a range of values (i)greater than A (in the traditional sense) and less than B (in thetraditional sense), (ii) greater than or equal to A and less than B (inthe traditional sense), (iii) greater than A (in the traditional sense)and less than or equal to B, and (iv) greater than or equal to A andless than or equal to B. To avoid any potential confusion, thetraditional use of these terms “greater than and “less than,” to theextent that they are used at all thereafter herein, shall be referred toby “greater than and only greater than” and “less than and only lessthan,” respectively.

Important with respect to several advantages of the present invention,the tester 10 includes a connector J1 to which test cable 28 isremovably connected. Having the test cable 28 be removably connected tothe tester 10 among other things (i) permits different test cables(cables of FIGS. 5A, 7A, and 8) to be used with a single tester therebyallowing a wider range of functions to be performed with the tester 10,(ii) permits an optional extender cable (cable of FIGS. 6A and 6B) to beused, thereby allowing the tester 10 to be used by one person sitting ina driver's seat for some tests, but allowing a shorter cable (FIG. 5A)to be used for others, and (iii) allows the tester 10 to be storedseparately from the cable.

Referring more specifically to FIG. 1B, the tester 10 of the presentinvention preferably includes an electronic test circuit 14 that teststhe starting/charging system 11, which test circuit 14 preferablyincludes a discrete test circuit 40 in circuit communication with anassociated processor circuit 42. In the alternative, the test circuit 14can consist of discrete test circuit 40 without an associated processorcircuit. In either event, preferably, the tester 10 of the presentinvention also includes a detection circuit 44 in circuit communicationwith the test circuit 40 and/or the processor circuit 42. The testcircuit 40 preferably accepts at least one test signal 46 from thestarting/charging system 11 via the cable 28 and connector J1. Thedetection circuit 44 preferably accepts at least one detection signal 48from the tester cable 28 or other device (e.g., sensor cable of FIG. 8)placed in circuit communication with the tester 10 via connector J1.Tester 10 also preferably includes a power circuit 60 allowing thetester 10 to be powered by either the starting/charging system 11 viapower connection 61 or by an internal battery 62.

The processor circuit 42, also referred to herein as just processor 42,may be one of virtually any number of processor systems and/orstand-alone processors, such as microprocessors, microcontrollers, anddigital signal processors, and has associated therewith, eitherinternally therein or externally in circuit communication therewith,associated RAM, ROM, EPROM, clocks, decoders, memory controllers, and/orinterrupt controllers, etc. (all not shown) known to those in the art tobe needed to implement a processor circuit. One suitable processor isthe SAB-C501G-L24N microcontroller, which is manufactured by Siemens andavailable from various sources. The processor 42 is also preferably incircuit communication with various bus interface circuits (BICs) via itslocal bus 64, e.g., a printer interface 66, which is preferably aninfrared interface, such as the known Hewlett Packard (HP) infraredprinter protocol used by many standalone printers, such as model number82240B from HP, and which communicates via infrared LED 67. The userinput 16, e.g., switches 18-21, preferably interfaces to the tester 10via processor 42. Likewise, the display 24 preferably is interfaced tothe tester 10 via processor 42, with the processor 42 generating theinformation to be displayed on the display 24. In addition thereto, orin the alternative, the tester 10 may have a second display 68 (e.g.,one or more discrete lamps or light emitting diodes or relays foractuation of remote communication devices) in circuit communication withthe test circuit 40.

Referring now to FIG. 2, a more detailed block diagram showing animplementation of the test circuit 40 and detection circuit 44 is shown.In the particular implementation of FIG. 2, the test circuit 40 anddetection circuit 44 are implemented using a digital-to-analog converter(DAC) 80 that is in circuit communication with processor 42 via bus 81and in circuit communication with a number of comparators 82 viareference voltage outputs 83, which comparators 82 in turn are incircuit communication with the processor 42 via test signals 85.Although the test circuit 40 and detection circuit 44 need not be soimplemented, having at least a portion of the test circuit 40 beimplemented using a DAC 80 and a comparator 82 in circuit communicationwith the processor 42 provides certain benefits, as explained below.

The detection circuit 44 preferably includes a detection front end 84and a comparator 82 a. The detection front end 84 preferably accepts asan input the detection signal 48 and generates an output 86 to thecomparator 82 a. Referring to FIG. 3A, a circuit implementation of thedetection circuit 44 is shown schematically. The preferredimplementation of the detection front end 84 is shown as circuitry 90 tothe left of node 92. The circuitry shown includes a connection J1-6,J1-7, J1-8 to the battery of the starting/charging system 11, a PTC F2(positive temperature coefficient device that acts as a sort ofautomatically resetting fuse), a diode D7, a voltage divider created byresistors R14 and R15, and a connection to detection signal 48 at J1-4via resistor R29. The component values are preferably substantially asshown. Processor 42, via bus 81, causes DAC 80 to generate a particularvoltage on reference voltage line 83 a, which is input to comparator 82a. The detection front end 90 generates a particular detection voltageat node 92, depending on what signals are presented at power signal 61and detection signal 48. The comparator 82 a will output a logical ONEor a logical ZERO to processor 42 depending on the relative values ofthe reference voltage 83 a and the detection voltage at node 92. Thus,to detect which cable 28 or device is attached to connector J1, theprocessor 42 need only send a command to DAC 80 via bus 81, wait aperiod of time for the various voltages to stabilize, and read a binaryinput from input 85 a.

Various connection scenarios for detection front end circuitry 90 areshown in FIGS. 3B-3F, which correspond to various test cables 28 andother signals connected to connector J1. In each, the voltage at node 92is determined using straightforward, known resistor equations, e.g.,resistor voltage divider equations, equivalent resistances for resistorsin series, and equivalent resistance for resistors in parallel, etc. InFIG. 3B, the power signal 61 is connected to the battery, which presentsa battery voltage V_(BATT), and the detection signal 48 (shown in FIG.3A) is left as an open circuit; therefore, the test voltage at node 92is approximately 0.1·V_(BATT), because the battery voltage V_(BATT) isdivided by resistors R14 (90.9 KΩ) and R15 (10.0 KΩ). In FIG. 3C, thepower signal 61 is connected to the battery, which presents a batteryvoltage V_(BATT), and the detection signal 48 is grounded to the batteryground; therefore, the test voltage at node 92 is approximately0.5·V_(BATT), because in this scenario the battery voltage is divided byR14 (90.9 KΩ) and the combination of R15 (10.0 KΩ) and R29 (10.0 KΩ) inparallel (5.0 KΩ combined resistance). In FIG. 3D, the power signal 61(shown in FIG. 3A) is left as an open circuit, and the detection signal48 is connected to an applied voltage V_(A); therefore, the test voltageat node 92 is ½V_(A), because the applied voltage V_(A) is dividedequally by resistors R29 (10.0 KΩ) and R15 (10.0 KΩ). In FIG. 3E, thepower signal 61 is connected to the battery, which presents a batteryvoltage V_(BATT), and the detection signal 48 is grounded to the batteryground via an additional resistor R29′; therefore, the test voltage atnode 92 is the following function of V_(BATT),$V_{92} = {\frac{{Re}\quad q}{{{Re}{\quad \quad}q} + R_{14}} \cdot V_{{BATT}}}$where${{Re}\quad q} = \frac{1}{\frac{1}{R15} + \frac{1}{{R29} + {R29}^{\prime}}}$

because in this scenario the battery voltage is divided by R14 and thecombination of R15 in parallel with R29 and R29′ in series, which isabout 0.07·V_(BATT) if R29′ is 10.0 KΩ. Finally, in FIG. 3F, the powersignal 61 (shown in FIG. 3A) is open circuit and the detection signal 48(shown in FIG. 3A) is open circuit; therefore, the voltage at node 92 ispulled to ground by resistor R15. In al these scenarios, power ground 94is preferably connected to signal ground 96 either at the negativebattery terminal or within test cable 28. The processor 42, DAC 80, andcomparator 82 a preferably use the known successive approximation methodto measure the voltage generated by the detection circuit front end 84.

Thus, in the general context of FIGS. 1A, 1B, 2, and 3A-3F, a specifictest cable 28 connected to connector J1 will cause the voltage 86 (i.e.,the voltage at node 92) to be a specific voltage, which is measuredusing the successive approximation method. The processor 42 thenpreferably determines from that voltage 86 which cable 28 is connectedto the tester at connector J1 and executes appropriate codecorresponding to the particular cable 28 connected to the connector J1.Various specific connectors 28 are described below in connection withFIGS. 5A-5C, 6A-6B, 7A-7C, and 8.

Referring back to FIG. 2, the test circuit 40 preferably includes avoltmeter circuit 100 and a diode ripple circuit 102. The voltmetercircuit 100 is preferably implemented using a DAC 80 and comparator 82b, to facilitate testing the starting portion of the starting/chargingsystem 11. In the preferred embodiment, the voltmeter circuit 100comprises an autozero circuit 104 in circuit communication with a signalconditioning circuit 106. The autozero circuit 104 preferably accepts asan input the test signal 46. The signal conditioning circuit 106generates a test voltage 107 that is compared to a reference voltage 83b by comparator 82 b, which generates test output 85 b. Similarly, thediode ripple circuit 102 is preferably implemented using a DAC 80 andcomparator 82 c. In the preferred embodiment, the diode ripple circuit102 comprises a bandpass filter 108 in circuit communication with asignal conditioning circuit 110, which in turn is in circuitcommunication with a peak detect circuit 112. The diode ripple circuit102 accepts as an input the test signal 46. The peak detect circuit 112generates a test voltage 114 that is compared to a reference voltage 83c by comparator 82 c, which generates test output 85 c.

Referring now to FIG. 4A, a schematic block diagram of a preferredembodiment of the voltmeter circuit 100 is shown. The signalconditioning circuit 106 preferably comprises a protective Zener diodeZ4 and amplifier circuit 115. Amplifier circuit 115 preferably comprisesan operational amplifier U8-A and associated components resistor R16,resistor R20, capacitor C21, capacitor C45, and diode D12, connected incircuit communication as shown. Amplifier circuit 115 generates testsignal 107 as an input to comparator 82 b. The processor 42, DAC 80,amplifier circuit 115, and comparator 82 b preferably use the knownsuccessive approximation method to measure the voltage input to theamplifier 115, which is either the signal 46 or a ground signalgenerated by the autozero circuit 104 responsive to the processor 42activating transistor Q1. After using the successive approximationmethod, the processor 42 has determined a value corresponding to andpreferably representing the voltage at 46. The autozero circuit 104preferably comprises a transistor Q1 in circuit communication withprocessor 42 via an autozero control signal 116. Ordinarily, the signal46 from cable 28 passes through resistor R26 to amplifier 115. However,responsive to the processor 42 asserting a logical HIGH voltage(approximately 5 VDC) onto the autozero control signal 116, transistorQ1 conducts, causing the signal 46 to be pulled to signal ground 96through resistor R26. As known to those in the art, the voltage measuredat signal 107 while the autozero control signal 116 is asserted is usedas an offset for voltage measurements taken with voltmeter 100 and isused to offset the value corresponding to and preferably representingthe voltage at 46.

Having the voltmeter 100 be implemented in this manner, i.e., with aprocessor, a DAC, and a comparator, provides several benefits. Onebenefit is reduced cost associated with not having to have a discreteanalog-to-digital converter in the circuit. Another benefit isdemonstrated during the test of the starting portion of thestarting/charging system 11. In that test, the test circuit 40 waits forthe battery voltage to drop to a predetermined threshold value, whichindicates that a user has turned the key to start the starter motor. Thevoltage drops very rapidly because the starter motor presents almost ashort circuit to the battery before it begins to rotate. The particularimplementation of FIG. 4A facilitates the process of detecting thevoltage drop by permitting the processor 42 to set the threshold voltagein the DAC 80 once and then continuously read the input port associatedwith input 85 b from comparator 82 b. As the battery voltage drops tothe threshold voltage set in DAC 80, the output comparator almostinstantaneously changes, indicating to processor 42 that the voltagedrop has occurred.

Referring now to FIG. 4B, a schematic block diagram of the diode ripplecircuit 102 is shown. As discussed above, in the preferred embodiment,the diode ripple circuit 102 comprises a bandpass filter 108 in circuitcommunication with a signal conditioning circuit 110, which in turn isin circuit communication with a peak detect circuit 112. The bandpassfilter 108 preferably comprises operational amplifier U14-A andassociated components—resistor R46, resistor R47, resistor R48,capacitor C40, capacitor C41, and Zener diode Z1—connected as shown.Zener diode Z1 provides a pseudo-ground for the AC signal component ofsignal 46. The bandpass filter 108 has a gain of approximately 4.5 andhas bandpass frequency cutoff values at approximately 450 Hz and 850 Hz.Signal 109 from bandpass filter 108 is then conditioned using signalconditioner 110. Signal conditioner 110 preferably comprises anamplifier U14-B and a transistor Q10 and associated components—resistorR11, resistor R47, resistor R49, resistor R50, and Zener diodeZ1—connected as shown. Signal conditioner circuit 110 generates a DCsignal 111 corresponding to the amplitude of the AC signal component ofsignal 46. The resulting signal 111 is then input to peak detector 112,preferably comprising diode D9, resistor R51, and capacitor C42,connected as shown, to generate signal 114. The signal 114 from the peakdetect circuit 112 is measured by the processor 42, DAC 80, andcomparator 82 c using the successive approximation method. This value iscompared to a threshold value, preferably by processor 42, to determineif excessive diode ripple is present. An appropriate display isgenerated by the processor 42. In the alternative, the signal 85 c canbe input to a discrete display to indicate the presence or absence ofexcessive diode ripple.

Referring once again to FIG. 2, test circuit 40 further has a batterytester component 117. The battery tester component 117 includes a testcurrent generator circuit 118 and an AC voltage amplifier/convertercircuit 119. The battery tester component 117 is preferably implementedusing DAC 80 and a comparator 82 d, to facilitate the testing of abattery. The test current generator circuit 118 preferably applies aload current to the battery under test. The AC voltageamplifier/converter circuit 119 measures the voltage generated by theload current applied to the battery. The measuring preferably includesamplifying the voltage and converting it to a ground referenced DCvoltage.

In this regard, reference is now made to FIG. 4C where the preferredembodiment of test current generator circuit 118 is illustrated. Thecircuit 118 includes resistors R21, R22, R27, R28, R36, R37, R40, andR42, capacitors C24, C28, C29, and C33, operational amplifiers U10-A andU10-B, and transistors Q6, Q8, and Q9, all interconnected as shown. Inoperation, processor 42 and DAC 80 together produce a variable voltagepulse signal that is output on node 122. A filter is formed by resistorsR28, R27, R36, capacitors C24 and C28 and amplifier U10-B, whichconverts the signal on node 122 to a sine wave signal. The sine wavesignal is applied to a current circuit formed by amplifier U10-A, R22,C29, Q6, Q8, and R40 arranged in a current sink configuration. Morespecifically, the sine wave signal is applied to the “+” terminal ofamplifier Q10-A. The sine wave output of amplifier of Q10-A drives thebase terminal of Q6 which, in turn, drives the base terminal of Q8 togenerate or sink a sine wave test current. This causes the sine wavetest current to be applied to the battery under test through terminal 61(+POWER). It should also be noted that an enable/disable output 121 fromprocessor 42 is provided as in input through resistor R36 to amplifierU10-B. The enable/disable output 121 disables the test current generatorcircuit 118 at start-up until DAC 80 has been initialized. Also, a surgesuppressor F2 and diode D7 are provided to protect the circuitry fromexcessive voltages and currents. As described above, the test currentgenerates a voltage across the terminals of the battery, which ismeasured by AC voltage amplifier/converter circuit 119. This AC voltageis indicative of the battery's internal resistance.

Referring now to FIG. 4D, AC voltage amplifier/converter circuit 119will now be discussed in more detail. The circuit is formed of twoamplifier stages and a filter stage. The first amplifier stage is formedby diodes D3 and D5, resistors R30, R31, R32, R33, R34, amplifier U9-A,and zener diode Z5. The second amplifier stage is formed by resistorsR9, R24, R25, and R17, capacitor C27, amplifier U9-B, and transistor Q4.The filter stage is formed by resistors R8, R18, R19, capacitors C15,C17, and C19, and amplifier U7-A.

In operation, the AC voltage to be measured appears on node 46 (+SENSE)and is coupled to amplifier U9-A through C32, which removes any DCcomponents. An offset voltage of approximately 1.7 volts is generated byresistors R33 and R34 and diodes D3 and D5. Resistor R32 and zener diodeZ5 protect amplifier U9-A against excessive input voltages. The gain ofamplifier U9-A is set by resistors R30 and R31 and is approximately 100.Hence, the amplified battery test voltage is output from amplifier U9-Ato the second amplifier stage.

More specifically, the amplified battery test voltage is input throughcapacitor C27 to amplifier U9-B. Capacitor C27 blocks any DC signalcomponents from passing through to amplifier U9-B. Resistors R9 and R25and zener diode Z3 bias amplifier U9-B. Coupled between the output and(−) input of amplifier U9-B is the emitter-base junction of transistorQ4. The collector of Q4 is coupled to the ground bus through resistorR17. In essence, the second amplifier stage rectifies the decoupled ACsignal using amplifier U9-B and transistor Q4 to invert only thoseportions of the decoupled AC signal below approximately 4.1 volts andreferencing the resulting inverted AC signal, which appears across R17,to the potential of the ground bus. The resulting AC signal is provideddownstream to the filter stage.

Input to the filter stage is provided through a resistor-capacitornetworked formed by resistors R18, R19, and R8, and capacitors C17 andC19. Amplifier U7-A and feedback capacitor C15 convert the AC inputsignal at the (+) input of the amplifier U7-A to a DC voltage that isoutput to node 120. Node 120 provides the DC voltage as an input to the(−) terminal of comparator 82 d. The (+) terminal of comparator 82 dreceives the output of DAC 80 on node 83 d. The output of comparator 82d is a node 85 d that is in circuit communication with an data input onprocessor 42. Through DAC 80 and comparator 82 d, processor can use asuccessive approximation technique to determine the amplitude of the DCvoltage on node 120 and, therefore, ultimately the internal resistanceof the battery under test. This internal resistance value, along withuser input information such as the battery's cold-cranking ampere(hereinafter CCA) rating, can determine if the battery passes or failsthe test. If the battery fails the test, replacement is suggested.Additional battery tester circuitry can be found in U.S. Pat. Nos.5,572,136 and 5,585,728, which are hereby fully incorporated byreference.

Referring now to FIGS. 5A-5C, a two-clamp embodiment 128 of a test cable28 is shown. The cable 128 of this embodiment preferably comprises afour-conductor cable 130 in circuit communication with a connector 132at one end, connected as shown in FIGS. 5B and 5C, and in circuitcommunication with a pair of hippo clips 134, 136 at the other end. Thecable 128 is preferably about three (3) feet long, but can be virtuallyany length. The connector 132 mates with connector J1 of tester 10. Thefour conductors in cable 130 are preferably connected to the hippo clips134, 136 so as to form a Kelvin type connection, with one conductorelectrically connected to each half of each hippo clip, which is knownin the art. In this cable 128, the power ground 94 and signal ground 96are preferably connected to form a star ground at the negative batteryterminal. Resistor R128 connects between the +sense and −sense lines. Intest cable 128, pin four (4) is open; therefore, the equivalent circuitof the detection circuit 44 for this cable 128 is found in FIG. 3B. Morespecifically, with the hippo clips 134, 136 connected to a battery of astarting/charging system 11, and connector 132 connected to matingconnector J1 on tester 10, the equivalent circuit of the detectioncircuit 44 for this cable 128 is found in FIG. 3B. The processor 42determines the existence of this cable 128 by (i) measuring the batteryvoltage V_(BATT) using voltmeter 100, (ii) dividing the battery voltageV_(BATT) by ten, and (iii) determining that the voltage at node 92 isabove or below a threshold value. In this example the threshold value isdetermined to be approximately two-thirds of the way between twoexpected values or, more specifically, (V_(BATT)/20+V_(BATT)/10.5)/1.5.If above this value, then cable 128 is connected.

Referring now to FIGS. 6A-6B, an embodiment of an extender cable 228 isshown. The cable 228 of this embodiment preferably comprises afour-conductor cable 230 in circuit communication with a first connector232 at one end and a second connector 234 at the other end, connected asshown in FIG. 6B. The cable 128 is preferably about twelve (12) feetlong, but can be virtually any length. Cable conductors 230 a and 230 bare preferably in a twisted pair configuration. Cable conductor 230 d ispreferably shielded with grounded shield 231. Connector 232 mates withconnector J3 of tester 10. Connector 234 mates with connector 132 ofcable 128 of FIGS. 5A-5C (or, e.g., with connector 332 of cable 328(FIGS. 7A-7C) or with connector 432 of cable 428 (FIG. 8)). In cable228, the power ground 94 and signal ground 96 are not connected to forma star ground; rather, the extender cable 228 relies on another testcable (e.g., cable 128 or cable 328 or cable 428) to form a star ground.In cable 228, pin four (4) of connector 232 (detection signal 48 in FIG.3A) is grounded to signal ground 96 (pin eleven (11)) via connection236; therefore, the equivalent circuit of the detection circuit 44 forthis cable 128 is found in FIG. 3C. More specifically, with a cable 128connected to connector 234, and with the hippo clips 134, 136 of cable128 connected to a battery of a starting/charging system 111, andconnector 232 connected to mating connector J1 on tester 10, theequivalent circuit of the detection circuit 44 for this cablecombination 128/228 is found in FIG. 3C. The processor 42 determines theexistence of this cable 128 by (i) measuring the battery voltageV_(BATT) using voltmeter 100, (ii) dividing the battery voltage V_(BATT)by twenty and, (iii) determining that the voltage at node 92 is above orbelow a threshold value. In this example the threshold value isdetermined to be approximately two-thirds of the way between twoexpected values or, more specifically, (V_(BATT)/20+V_(BATT)/10.5)/1.5.If below this value, then cable 128 is connected.

In response to detecting an extended cable combination 128/228, theprocessor 42 may perform one or more steps to compensate the electronicsin the test circuit for effects, if any, of adding the significantlength of wiring inside cable 228 into the circuit. For example, voltagemeasurements taken with voltmeter 100 might need to be altered by a fewpercent using either a fixed calibration value used for all extendercables 228 or a calibration value specific to the specific cable 228being used. Such a calibration value might take the form of an offset tobe added to or subtracted from measurements or a scalar to be multipliedto or divided into measurements. Such alterations could be made to rawmeasured data or to the data at virtually any point in the testcalculations, responsive to determining that the extender cable 228 wasbeing used.

Referring now to FIGS. 7A-7C, a probe embodiment 328 of a test cable 28is shown. The cable 328 of this embodiment preferably comprises atwo-conductor cable 330 in circuit communication with a connector 332 atone end, connected as shown in FIGS. 7B and 7C, and in circuitcommunication with a pair of probes 334, 336 at the other end. The cable328 is preferably about three (3) feet long, but can be virtually anylength. The connector 332 mates with connector J1 of tester 10. In thiscable 328, the power ground 94 and signal ground 96 are connected byconnection 338 inside housing 340 of connector 332 to form a star groundinside housing 340. In cable 328, the battery power signal 48 is openand the detection signal 61 (pin four (4) of connector J1) is open;therefore, the equivalent circuit of the detection circuit 44 for thiscable 328 is found in FIG. 3F. More specifically, with connector 332connected to mating connector J1 on tester 10, the equivalent circuit ofthe detection circuit 44 for this cable 328 is found in FIG. 3F, i.e.,the voltage at node 92 is at zero volts or at about zero volts. Theprocessor 42 determines the existence of this cable 328 by (i) measuringthe battery voltage V_(BATT), (ii) dividing the battery voltage V_(BATT)by a predetermined value such as, for example, ten or twenty, and (iii)determining that the voltage at node 92 is above or below a thresholdvalue.

The power circuit 60 allows the tester 10 to power up using the internalbattery 62 when using the cable 328 with probes. More specifically,pressing and holding a particular key, e.g., key 21, causes the internalbattery 62 to temporarily power the tester 10. During an initialstart-up routine, the processor determines the battery voltage usingvoltmeter 100 and determines that there is no battery hooked up viapower line 61. In response thereto, the processor 42 via control signal63 causes a switch, e.g., a MOSFET (not shown) in power circuit 60 toclose in such a manner that the tester 10 is powered by the internalbattery 62 after the key 21 is released.

Referring now to FIG. 8, a block diagram of a proposed sensor cable 428is shown. Sensor cable 428 is preferably an active, powered device andpreferably comprises a four-conductor cable 430, a connector 432, apower supply circuit 434, an identification signal generator 436, acontrol unit 438, a sensor 440, a pre-amp 442, and a calibrationamplifier 446, all in circuit communication as shown in FIG. 8.Connector 432 mates with connector J1 of tester 10. Sensor cable 428 mayor may not be powered by a battery being tested and may therefore bepowered by the internal battery 62 inside tester 10. Accordingly, sensorcable 428 preferably comprises battery power connections 430 a, 430 b tothe internal battery 62. Power supply circuit 434 preferably comprises apower regulator (not shown) to generate from the voltage of battery 62the various voltages needed by the circuitry in sensor cable 428. Inaddition, power supply circuit 434 also preferably performs otherfunctions of known power supplies, such as various protection functions.The sensor cable 428 also preferably comprises an identification signalgenerator 436 that generates an identification signal 430 c thatinterfaces with detection circuit 44 of tester 10 to provide a uniquevoltage at node 92 for this particular cable 428. Identification signalgenerator 436 may, for example, comprise a Zener diode or an activevoltage regulator (neither shown) acting as a regulator on the internalbattery voltage to provide a particular voltage at 430 c, therebycausing the detection circuit to behave as in FIG. 3D, with the voltageat node 92 being about half the voltage generated by identificationsignal generator 436. In the alternative, another circuit of FIGS. 3B-3Fmay be used to uniquely identify the sensor cable 428. Sensor cable 428is preferably controlled by control unit 438, which may be virtually anycontrol unit, e.g., discrete state machines, a preprogrammed processor,etc. Control unit 438 preferably controls and orchestrates the functionsperformed by sensor cable 428. Sensor cable 428 also preferablycomprises a sensor 440, e.g., a Hall effect sensor, in circuitcommunication with a pre-amp 442, which in turn is in circuitcommunication with a calibration amplifier 446. Calibration amplifier446 outputs the signal 430 d, which is measured by voltmeter 100.Pre-amp 442 and calibration amplifier 446 may be in circuitcommunication with control unit 438 to provide variable gain control orautomatic gain control to the sensor cable 428. The particularidentification signal 430 c generated by ID generator 436 can be made tochange by control unit 438 depending on a particular gain setting. Forexample, if the sensor 440 is a Hall effect sensor and the sensor cable428 implements a current probe, the particular identification signal 430c generated by ID generator 436 can be set to one voltage value for anampere range of e.g. 0-10 Amperes and set to a different voltage valuefor an ampere range of e.g. 0-1000 Amperes, thereby specificallyidentifying each mode for the probe and maximizing the dynamic range ofthe signal 46 for each application. In this type of system, theprocessor 42 would need to identify the type of cable attached beforeeach measurement or periodically or in response to user input.

Referring now to FIG. 9 in the context of the previous figures, a veryhigh-level flow chart 500 for the operation of tester 10 is shown. Thetasks in the various flow charts are preferably controlled by processor42, which has preferably been preprogrammed with code to implement thevarious functions described herein. The flow charts of FIGS. 9-12 arebased on a tester 10 having a hippo clip cable 128 connected to anextender cable 228, which in turn is connected to tester 10 at connectorJ1. Starting at task 502, the user first powers up the tester 10 at task504 by connecting the tester 10 to a battery of a starting/chargingsystem 11. If the tester 10 is to be powered by internal battery 62, theuser presses and holds the button 21 until the processor 42 latches thebattery 62, as described above. In response to the system powering up,the processor 42 initializes the tester 10, e.g., by performing variousself-tests and/or calibrations, such as autozeroing, described above.

Next, at task 506, the tester 10 detects the type of cable 28 attachedto connector J1, e.g., as being one of the cables 128, 228, 328, or 428,discussed above. In general, this is done by having the processormeasure the voltage at node 92 using a successive approximationtechnique with DAC 80 and comparator 82 a, comparing the measured valueof the voltage at node 92 to a plurality of voltage values, andselecting a cable type based on the measured voltage relative to thepredetermined voltage values. One or more of the plurality of voltagevalues may depend on, or be a function of, battery voltage; therefore,the processor may measure the battery voltage and perform variouscomputations thereon as part of determining the plurality of voltagevalues such as, for example, those described in connection with FIGS.5A-7B, above. Then, the user tests the starting/charging system 11, attask 508, and the testing ends at task 510.

Referring now to FIG. 10, a medium-level flow chart is presented showinga preferred program flow for the testing of the starting/charging systemand also showing some of the beneficial aspects of the user interfaceaccording to the present invention. The test routine 508 preferablyperforms a starter test, a plurality of charger tests, and a dioderipple test. The tester 10 preferably accepts input from the user (e.g.,by detecting various keys being pressed) to allow the user to look overresults of tests that have already been performed and to either skip orredo tests that have already been performed. In general, preferably theuser presses one key to begin a test or complete a test or to indicateto the processor 42 that the vehicle has been placed into a particularstate. The user presses a second key to look at the results ofpreviously completed tests and the user presses a third key to skiptests that have already been performed. Code implementing the userinterface preferably conveys to the user via the display 24 whether atest may be skipped or not. More specifically to the embodiment shown inthe figures, the user presses the star button 18 to cause the processorto begin a test or complete a test or to indicate to the processor 42that the vehicle has been placed into a particular test state, therebyprompting the processor to take one or more measurements. After one ormore tests are performed, the user may press the up button 19 to reviewthe results of tests that have been performed. Thereafter, the user mayskip or redo tests that have already been done. The user may skip a testthat has already been done by pressing the down button 20.

More particular to FIG. 10, starting at 520, the routine 508 firstperforms the starter test, at 522. As will be explained below in thetext describing FIGS. 11 and 12, for the various tests the user isprompted via the display 24 to place the vehicle into a particular stateand to press a key when the vehicle is in that state, then the tester 10takes one or more measurements, then the data is processed, and thentest results are displayed to the user via display 24.

In the preferred embodiment, there are five test states: a starter teststate 522, a first charger test state 524, a second charger test state526, a third charger test state 528, and a diode ripple test state 530.The tester successively transitions from one state to the next as eachtest is completed. There is also a finished state 531 which is enteredafter all of the tests are completed, i.e., after the diode ripple testis completed. For each test, preferably the user is prompted via thedisplay 24 to place the vehicle into a particular state, the userpresses the star key 18 to indicate that the vehicle is in that state,then the tester 10 takes one or more measurements, then the data isprocessed, then test results are displayed to the user via display 24,then the user presses the start key 20 to move to the next test. As eachtest is completed, the processor 42 sets a corresponding flag in memoryindicating that that test has been completed. These flags allow the codeto determine whether the user may skip a test that has already beenperformed. As shown, the user presses the star key 18 to move to thenext test. As shown in FIG. 10, if the user presses the down key 20while in any of the various states, the code tests whether that test hasbeen completed, at 532 a-532 e. If so, the code branches to the nextstate via branches 534 a-534 e. If not, the code remains in that stateas indicated by branches 536 a-536 e. If the user presses the up key 19,while in any of states 524-530, the code branches to the previous teststate, as indicated by branches 538 a-538 e. Thus, the user may use theup key 19 to look at previously performed tests, and selectively useeither (a) the down key 20 to skip (keep the previously recorded datarather than collecting new data) any particular test that has beenperformed or (b) the star key 18 to redo any particular test that hasalready been performed. For example, assume that a vehicle has passedthe Starter Test 522, failed Charger Test No. 1 524, passed Charger TestNo. 2 526, and passed Charger Test No. 3 528. In this situation, theuser may want to redo Charger Test No. 1 without having to redo theother two tests. In that case, the user may hit the up key 19 twice tomove from state 528 to the Charger Test No. 1, which is state 524. Inthat state, the user may perform Charger Test No. 1 again. Afterperforming Charger Test No. 1 again, the user may move to the next test,the Diode Ripple Test 530, by actuating the down key twice (if in state526) or thrice (if still in state 524), thereby skipping the ChargerTest No. 2 and Charger Test No. 3 and retaining the previously collecteddata for those tests.

After all the tests are complete, the tester 10 enters the All TestsComplete state 531. While in this state, the user may actuate the up key19 to view one or more previously completed tests or may actuate thestar key 18 to return, at 540.

Referring now to FIGS. 11A-11D and 12, additional aspects of theroutines discussed in connection with FIG. 10 are shown. FIGS. 11A-11Dare set up similarly to FIG. 10; however, the symbols representing thedecisions at 532 a-532 e and branches at 536 a-536 e in FIG. 10 havebeen compressed to conserve space in FIGS. 11A-11D. FIGS. 11A-11D focuson the user interface of the present invention and provide additionalinformation about the various tests. FIG. 12 provides additionalinformation about the starter test while de-emphasizing the userinterface. The small diamonds extending to the right from the various“down arrow” boxes in FIGS. 11A-11D represent those decisions 532 a-532e and branches back to the same state 536 a-536 e, as will be furtherexplained below;

Starting at 600 in FIG. 11A, the test routine 508 first prompts the userat 602 to turn the engine off and to press the star key 18 when that hasbeen done. The user pressing the star key 18 causes the code to branchat 604 to the next state at 606. At state 606, the user is prompted toeither start the engine of the vehicle under test or press the star key18 to abort the starter test, causing the code to branch at 608 to thenext state at 610.

While in state 610, the tester 10 repeatedly tests for the star key 18being actuated and tests for a drop in the battery voltage indicative ofthe starter motor starting to crank, as further explained in the textaccompanying FIG. 12. If an actuation of the star key 18 is detected,the code branches at 611 and the starter test is aborted, at 612. If avoltage drop indicative of the start of cranking is detected, the tester10 collects cranking voltage data with voltmeter 100, as furtherexplained in the text accompanying FIG. 12. If the average crankingvoltage is greater than 9.6 VDC, then the cranking voltage is deemed tobe “OK” no matter what the temperature is, the code branches at 618,sets a flag indicating that the cranking voltage during starting was“OK” at 620, sets a flag indicating that the starter test has beencompleted at 622, and the corresponding message is displayed at 624. Onthe other hand, if the average cranking voltage is less than 8.5 VDC,then the battery voltage during starting (“cranking voltage”) is deemedto be “Low” no matter what the temperature is, i.e., there might beproblems with the starter, the code branches at 630, sets a flagindicating that the cranking voltage during starting was “Low” at 632,sets a Starter Test Complete Flag indicating that the starter test hasbeen completed at 622, and the corresponding message is displayed at624. Finally, if the average cranking voltage is between 8.5 VDC and 9.6VDC, then the processor 42 needs temperature information to make adetermination as to the condition of the starter, and the code branchesat 633. Accordingly, the processor 42 at step 634 prompts the user withrespect to the temperature of the battery with a message via display 24such as, “Temperature above xx°?” where xx is a threshold temperaturecorresponding to the average measured cranking voltage. A sample tableof cranking voltages and corresponding threshold temperatures is foundat 954 in FIG. 12. On the one hand, if the user indicates that thebattery temperature is above the threshold temperature, then the codebranches at 636, sets a flag indicating that the cranking voltage duringstarting was “Low” at 632, sets the Starter Test Complete Flagindicating that the starter test has been completed at 622, and acorresponding “Low” message is displayed at 624. On the other hand, ifthe user indicates that the battery temperature is not above thethreshold temperature, then the code branches at 638, sets a flagindicating that the cranking voltage during starting was “OK” at 620,sets the Starter Test Complete Flag indicating that the starter test hasbeen completed at 622, and a corresponding “OK” message is displayed at624. While in state 624, if the user presses the star key 18, the codebranches at 660 to state 662.

The No Load/Curb Idle charger test begins at state 662, in which theuser is prompted to adjust the vehicle so that the starting/chargingsystem is in a No Load/Curb Idle (NLCI) condition, e.g., very few if anyuser-selectable loads are turned on and no pressure is being applied tothe accelerator pedal. The battery voltage of the vehicle while in theNLCI condition provides information about the condition of theregulator's ability to regulate at its lower limit; the battery voltagewith the vehicle in the NLCI condition should be within a particularrange. Once the user has adjusted the vehicle to be in this condition,the user presses the star key 18, causing the code to branch at 664 totask 668 in which the tester 10 measures the battery voltage usingvoltmeter 100. The battery voltage may be measured once or measured anumber of times and then averaged or summed. It is preferably measured aplurality of times and averaged. In either event, a determination ismade as to whether the battery voltage (or average or sum) is within anacceptable range while in the NLCI condition. The end points of thisrange are preferably determined as functions of battery base voltage(battery voltage before the vehicle was started), V_(b). These endpointsare preferably calculated by adding fixed values to the base voltageV_(b), e.g., V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In thealternative, these endpoints can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking fixed percentages of the base voltage V_(b). The range selectedfor the embodiment shown in the figures is between V_(b)+0.5 VDC andV_(b)=15 VDC. If the battery voltage (or average or sum) is betweenthose endpoints with the vehicle in the NLCI condition, then theregulator is probably in an acceptable condition with respect to itslower limit of regulation. If the battery voltage (or average or sum) isless than V_(b)+0.5 VDC with the vehicle in the NLCI condition, then thebattery voltage (or average or sum) is lower than acceptable and/orexpected. If the battery voltage (or average or sum) is greater thanV_(b)=15 VDC with the vehicle in the NLCI condition, then the batteryvoltage (or average or sum) is higher than acceptable and/or expected.The code continues at 670 to task 672, where a NLCI Test Complete Flagis set indicating that the NLCI test has been performed. Then at 674,the code continues to state 676, in which the results of the NLCI testare displayed. Preferably, the following information is displayed toallow the user to make a determination as to whether the regulator is inan acceptable condition: base battery voltage and the battery voltagewith the vehicle in the NLCI condition. Also, if the battery voltagewith the vehicle in the NLCI condition was below the acceptable/expectedrange, a “Low” indication is presented to the user near the test batteryvoltage. Similarly, if the battery voltage with the vehicle in the NLCIcondition was above the acceptable/expected range, a “Hi” indication ispresented to the user near the test battery voltage. With thisinformation, the user can make a determination as to whether theregulator is in an acceptable condition with respect to its lowerregulation limit. While in state 676, if the user presses the star key18, the code branches at 678 to state 690.

The No Load/Fast Idle charger test begins at state 690, in which theuser is prompted to adjust the vehicle so that the starting/chargingsystem is in a No Load/Fast Idle (NLFI) condition, e.g., very few if anyuser-selectable loads are turned on and pressure is being applied to theaccelerator pedal to cause the vehicle motor to operate at about 2000revolutions per minute (RPM). The battery voltage of the vehicle whilein the NLFI condition provides information about the condition of theregulator's ability to regulate at its upper limit; the battery voltagewith the vehicle in the NLFI condition should be within a particularrange. Once the user has adjusted the vehicle to be in this condition,the user presses the star key 18, causing the code to branch, at 692, totask 694 in which the tester 10 measures the battery voltage usingvoltmeter 100. The battery voltage may be measured once or measured anumber of times and then averaged or summed. Preferably it is measured anumber of times and then averaged. In either event, a determination ismade as to whether the battery voltage (or average or sum) is within anacceptable range while in the NLFI condition. The end points of thisrange are preferably determined as functions of battery base voltage(battery voltage before the vehicle was started), V_(b). These endpointsare preferably calculated by adding fixed values to the base voltageV_(b), e.g., V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In thealternative, these endpoints can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking fixed percentages of the base voltage V_(b). The range selectedfor the embodiment shown in the figures is between V_(b)+0.5 VDC andV_(b)=15 VDC. If the battery voltage (or average or sum) is betweenthose endpoints with the vehicle in the NLFI condition, then theregulator is probably in an acceptable condition with respect to itsupper limit of regulation. If the battery voltage (or average or sum) isless than V_(b)+0.5 VDC with the vehicle in the NLFI condition, then thebattery voltage (or average or sum) is lower than acceptable and/orexpected. If the battery voltage (or average or sum) is greater thanV_(b)=15 VDC with the vehicle in the NLFI condition, then the batteryvoltage (or average or sum) is higher than acceptable and/or expected.The code continues at 696 to task 698, where a NLFI Test Complete Flagis set indicating that the NLFI test has been performed. Then at 700,the code continues to state 702, in which the results of the NLFI testare displayed. Preferably, the following information is displayed toallow the user to make a determination as to whether the regulator is inan acceptable condition: base battery voltage (battery voltage beforethe vehicle was started) and the battery voltage with the vehicle in theNLFI condition. Also, if the battery voltage with the vehicle in theNLFI condition was below the acceptable/expected range, a “Low”indication is presented to the user near the test battery voltage.Similarly, if the battery voltage with the vehicle in the NLFI conditionwas above the acceptable/expected range, a “Hi” indication is presentedto the user near the test battery voltage. With this information, theuser can make a determination as to whether the regulator is in anacceptable condition with respect to its upper regulation limit. Whilein state 702, if the user presses the star key 18, the code branches at704 to state 720.

The Full Load/Fast Idle charger test begins at state 720, in which theuser is prompted to adjust the vehicle so that the starting/chargingsystem is in a Full Load/Fast Idle (FLFI) condition, e.g., most if notall user-selectable loads (lights, blower(s), radio, defroster, wipers,seat heaters, etc.) are turned on and pressure is being applied to theaccelerator pedal to cause the vehicle motor to operate at about 2000RPM. The battery voltage of the vehicle while in the FLFI conditionprovides information about the condition of the alternator with respectto its power capacity; the battery voltage with the vehicle in the FLFIcondition should be within a particular range. Once the user hasadjusted the vehicle to be in this condition, the user presses the starkey 18, causing the code to branch, at 722, to task 724 in which thetester 10 measures the battery voltage using voltmeter 100. The batteryvoltage may be measured once or measured a number of times and thenaveraged or summed. Preferably it is measured a number of times and thenaveraged. In either event, a determination is made as to whether thebattery voltage (or average or sum) is within an acceptable range whilein the FLFI condition. The end points of this range are preferablydetermined as functions of battery base voltage (battery voltage beforethe vehicle was started), V_(b). These endpoints are preferablycalculated by adding fixed values to the base voltage V_(b), e.g.,V_(low)=V_(b)+0.5 VDC and V_(high)=15 VDC. In the alternative, theseendpoints can be determined by performing another mathematical operationwith respect to the base voltage V_(b), e.g., taking fixed percentagesof the base voltage V_(b). The range selected for the embodiment shownin the figures is between V_(b)+0.5 VDC and V_(b)=15 VDC. If the batteryvoltage (or average or sum) is between those endpoints with the vehiclein the FLFI condition, then the alternator is probably in an acceptablecondition with respect to its power capacity. If the battery voltage (oraverage or sum) is less than V_(b)+0.5 VDC with the vehicle in the FLFIcondition, then the battery voltage (or average or sum) is lower thanacceptable and/or expected. If the battery voltage (or average or sum)is greater than V_(b)=15 VDC with the vehicle in the FLFI condition,then the battery voltage (or average or sum) is higher than acceptableand/or expected. The code continues at 726 to task 728, where a FLFITest Complete Flag is set indicating that the FLFI test has beenperformed. Then at 730, the code continues to state 732, in which theresults of the FLFI test are displayed. Preferably, the followinginformation is displayed to allow the user to make a determination as towhether the alternator is in an acceptable condition: base batteryvoltage (battery voltage before the vehicle was started) and the batteryvoltage with the vehicle in the FLFI condition. Also, if the batteryvoltage with the vehicle in the FLFI condition was below theacceptable/expected range, a “Low” indication is presented to the usernear the test battery voltage. Similarly, if the battery voltage withthe vehicle in the FLFI condition was above the acceptable/expectedrange, a “Hi” indication is presented to the user near the test batteryvoltage. With this information, the user can make a determination as towhether the alternator is in an acceptable condition with respect to itspower capacity. While in state 732, if the user presses the star key 18,the code branches at 734 to state 750.

The alternator diode ripple test begins at state 750, in which the useris prompted to adjust the vehicle so that the starting/charging systemis in a Medium Load/Low Idle (MLLI) condition, e.g., the lights are on,but all other user-selectable loads (blower(s), radio, defroster,wipers, seat heaters, etc.) are turned off and pressure is being appliedto the accelerator pedal to cause the vehicle motor to operate at about1000 RPM. For the diode ripple test, the diode ripple circuit 102 isused and the processor measures the diode ripple voltage at 114 at theoutput of the peak detect circuit 112. The diode ripple voltage with thevehicle while in the MLLI condition provides information about thecondition of the diodes in the alternator with a known load (mostvehicle lights draw about 65 Watts of power per lamp). The diode ripplevoltage 114 with the vehicle in the MLLI condition should be less than apredetermined threshold, e.g., for the circuit of FIG. 4B less than 1.2VDC for a 12-volt system and less than 2.4 VDC for a 24-volt system.Once the user has adjusted the vehicle to be in this condition, the userpresses the star key 18, causing the code to branch, at 752, to task 754in which the tester 10 measures the ripple voltage using ripple circuit102. The ripple voltage 114 may be measured once or measured a number oftimes and then averaged or summed. Preferably it is measured a number oftimes and then averaged. In either event, a determination is made as towhether the ripple voltage 114 (or average or sum) is less than theacceptable threshold while in the MLLI condition. The threshold ripplevoltage selected for the embodiment shown in FIG. 4B is 1.2 VDC for a12-volt system and 2.4 VDC for a 24-volt system. If the ripple voltage114 is lower than that threshold with the vehicle in the MLLI condition,then the alternator diodes are probably in an acceptable condition. Thecode continues at 756 to task 758, where a Diode Ripple Test CompleteFlag is set indicating that the diode ripple test has been performed.Then at 760, the code continues to state 762, in which the results ofthe diode ripple test are displayed. Preferably, either a ripple voltage“OK” or ripple voltage “Hi” message is displayed, depending on themeasured ripple voltage relative to the threshold ripple voltage. Withthis information, the user can make a determination as to whether thealternator diodes are in an acceptable condition. While in state 762, ifthe user presses the star key 18, the code branches at 764 to state 770.

State 770 an extra state in that it is not a separate test of thestarting/charging system 11. As shown in FIG. 10 and discussed in theaccompanying text, the user may use the up key 19 (up button) and thedown key 20 (down button) to review the results of past tests, to redopreviously performed tests and/or skip (keep the data for) previouslyperformed tests. One implementation of this feature of the userinterface is shown in more detail in FIGS. 11A-11D. State 770 providesthe user with a state between the results of the last test and exitingthe test portion of the code so that the user can use the up key 19 anddown key 20 to review previous test results and skip and/or redo some ofthe tests. Pressing the star key 18 while in state 770 causes the codeto end, i.e., return, at 772.

While in state 602, in which the user is prompted to turn the engineoff, pressing the up key 19 does nothing (?please confirm). While instate 602, if the Starter Test has already been performed, i.e., if theStarter Test Complete Flag is set, e.g., at task 672, the displayconveys to the user that the down key 20 is active, e.g., by displayingan image corresponding to that key, such as an image of a downwardlypointing arrow. FIG. 13 shows a number of screens for display 26 showingthis feature of the user interface. Screen 1000 of FIG. 13 shows adisplay of a Starter Test prompt, before the Starter Test has beenperformed, i.e., with the Starter Test Complete Flag cleared. Screen1002 of FIG. 13 shows a display of the same Starter Test prompt, withthe Starter Test Complete Flag set, i.e., after the Starter Test hasbeen performed at least once since the tester 10 was last powered up.Note the presence of down arrow 1004 in screen 1002 that is not inscreen 1000, indicating that the down arrow key is active and may beused to skip the Starter Test.

Thus, while in state 602, pressing the down key 20 causes the code tobranch to a decision at 780 as to whether the Starter Test has alreadybeen performed, i.e., whether the Starter Test Complete Flag is set. Ifthe down key 20 is pressed while the Starter Test Complete Flag is notset, the code remains in state 602 and waits for the user to press thestar key 18, which will cause the Starter Test to be redone, startingwith branch 604. If the down key 20 is pressed while the Starter TestComplete Flag is set, the code branches at 782 to state 624, discussedabove, in which the results of the Starter Test are displayed. Thus,from state 602, if the Starter Test has already been performed, the usermay redo that test by pressing the star key 18, or may skip the test(thereby retaining the data and results from the previous execution ofthat test) by pressing the down key 20.

While in state 606, in which the user is prompted to start the engine,pressing the up key 19 causes the code to branch at 784 back to state602, discussed above. While in state 606, if the Starter Test hasalready been performed, i.e., if the Starter Test Complete Flag is set,e.g., at task 622, the display conveys to the user that the down key 20is active, e.g., by displaying an image corresponding to that key, suchas an image of a downwardly pointing arrow (e.g., down arrow 1004 in thescreen shots in FIG. 13). While in state 606, pressing the down key 20causes the code to branch to a decision at 786 as to whether the StarterTest has already been performed, i.e., whether the Starter Test CompleteFlag is set. If the down key 20 is pressed while the Starter TestComplete Flag is not set, the code remains in state 606 and waits forthe comparator 82 b (FIGS. 2 and 4A) to detect a crank and waits for theuser to press the star key 18, which will exit the Starter Test 612 viabranch 611. If the down key 20 is pressed while the Starter TestComplete Flag is set, the code branches at 788 to state 624, discussedabove, in which the results of the Starter Test are displayed. Thus,from state 606, the user may back up to the previous step by pressingthe up key 19 and, if the Starter Test has already been performed, theuser may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 624, in which the results of the Starter Test arepresented to the user, pressing the up key 19 causes the code to branchat 790 to a decision at 792 as to whether the user was prompted to entera battery temperature during the Starter Test, i.e., whether the batteryvoltage measured during cranking is between 8.5 VDC and 9.6 VDC andtherefore battery temperature is relevant to the cranking voltagedetermination. If so, the code branches at 794 to state 634, discussedabove, in which the user is prompted to enter data with respect tobattery temperature. If not, the code branches at 796 to state 606,discussed above, in which the user is prompted to start the engine.While in state 624, if the NLCI Test has already been performed, i.e.,if the NLCI Test Complete Flag is set, e.g., at task 672, the displayconveys to the user that the down key 20 is active, e.g., by displayingan image corresponding to that key, such as an image of a downwardlypointing arrow. Screen 1006 of FIG. 13 shows a display of the results ofa hypothetical Starter Test before the NLCI Test has been performed,i.e., with the NLCI Test Complete Flag cleared. Screen 1008 of FIG. 13shows a display of the same Starter Test results, with the NLCI TestComplete Flag set, i.e., after the NLCI Test has been performed at leastonce since the tester 10 was last powered up. Note the presence of downarrow 1004 in screen 1008 that is not in screen 1006, indicating thatthe down arrow key is active and may be used to skip to the results ofthe NLCI Test.

Thus, while in state 624, pressing the down key 20 causes the code tobranch to a decision at 800 as to whether the NLCI Test has already beenperformed, i.e., whether the NLCI Test Complete Flag is set. If the downkey 20 is pressed while the NLCI Test Complete Flag is not set, the coderemains in state 624 and waits for the user to press the star key 18,which will cause the code to branch to the beginning of the NLCI Test,via branch 660. If the down key 20 is pressed while the NLCI TestComplete Flag is set, the code branches at 802 to state 676, discussedabove, in which the results of the NLCI Test are displayed. Thus, fromstate 624, the user may back up to the previous step(s) by pressing theup key 19 and, if the NLCI Test has already been performed, the user mayredo that test by pressing the star key 18, or may skip the test(thereby retaining the data and results from the previous execution ofthat test) by pressing the down key 20.

While in state 662, which is the start of the NLCI Test, pressing the upkey 19 causes the code to branch at 804 to state 624, discussed above,in which the results of the Starter Test are presented. While in state662, if the NLCI Test has already been performed, i.e., if the NLCI TestComplete Flag is set, e.g., at task 672, the display conveys to the userthat the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 662, pressing the down key 20 causes the code to branch to adecision at 806 as to whether the NLCI Test has already been performed,i.e., whether the NLCI Test Complete Flag is set. If the down key 20 ispressed while the NLCI Test Complete Flag is not set, the code remainsin state 662 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 664.If the down key 20 is pressed while the NLCI Test Complete Flag is set,the code branches at 808 to state 676, discussed above, in which theresults of the NLCI Test are displayed. Thus, from state 662, the usermay back up to the previous test step (the end of the Starter Test) bypressing the up key 19 and, if the NLCI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 676, in which the results of the NLCI Test are presentedto the user, pressing the up key 19 causes the code to branch at 810 tostate 662, discussed above, in which the user is prompted to adjust thevehicle into the NLCI condition. While in state 676, if the NLFI Testhas already been performed, i.e., if the NLFI Test Complete Flag is set,e.g., at task 698, the display conveys to the user that the down key 20is active, e.g., by displaying an image corresponding to that key, suchas an image of a downwardly pointing arrow. Screen 1010 of FIG. 13 showsa display of the results of a hypothetical NLCI Test before the NLFITest has been performed, i.e., with the NLFI Test Complete Flag cleared.Screen 1012 of FIG. 13 shows a display of the same NLCI Test results,with the NLFI Test Complete Flag set, i.e., after the NLFI Test has beenperformed at least once since the tester 10 was last powered up. Notethe presence of down arrow 1004 in screen 1012 that is not in screen1010, indicating that the down arrow key is active and may be used toskip to the results of the NLFI Test.

Thus, while in state 676, pressing the down key 20 causes the code tobranch to a decision at 812 as to whether the NLFI Test has already beenperformed, i.e., whether the NLFI Test Complete Flag is set. If the downkey 20 is pressed while the NLFI Test Complete Flag is not set, the coderemains in state 676 and waits for the user to press the star key 18,which will cause the code to branch to the beginning of the NLFI Test,via branch 678. If the down key 20 is pressed while the NLFI TestComplete Flag is set, the code branches at 814 to state 702, discussedabove, in which the results of the NLFI Test are displayed. Thus, fromstate 676, the user may back up to the previous step (state 662) bypressing the up key 19 and, if the NLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 690, which is the start of the NLFI Test, pressing the upkey 19 causes the code to branch at 816 to state 676, discussed above,in which the results of the NLCI Test are presented. While in state 690,if the NLFI Test has already been performed, i.e., if the NLFI TestComplete Flag is set, e.g., at task 698, the display conveys to the userthat the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 690, pressing the down key 20 causes the code to branch to adecision at 820 as to whether the NLFI Test has already been performed,i.e., whether the NLFI Test Complete Flag is set. If the down key 20 ispressed while the NLFI Test Complete Flag is not set, the code remainsin state 690 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 692.If the down key 20 is pressed while the NLFI Test Complete Flag is set,the code branches at 822 to state 702, discussed above, in which theresults of the NLFI Test are displayed. Thus, from state 690, the usermay back up to the previous test step (the end of the NLCI Test) bypressing the up key 19 and, if the NLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 702, in which the results of the NLFI Test are presentedto the user, pressing the up key 19 causes the code to branch at 824 tostate 690, discussed above, in which the user is prompted to adjust thevehicle into the NLFI condition. While in state 702, if the FLFI Testhas already been performed, i.e., if the FLFI Test Complete Flag is set,e.g., at task 728, the display conveys to the user that the down key 20is active, e.g., by displaying an image corresponding to that key, suchas an image of a downwardly pointing arrow. Screen 1014 of FIG. 13 showsa display of the results of a hypothetical NLFI Test before the FLFITest has been performed, i.e., with the FLFI Test Complete Flag cleared.Screen 1016 of FIG. 13 shows a display of the same NLFI Test results,with the FLFI Test Complete Flag set, i.e., after the FLFI Test has beenperformed at least once since the tester 10 was last powered up. Notethe presence of down arrow 1004 in screen 1016 that is not in screen1014, indicating that the down arrow key is active and may be used toskip to the results of the FLFI Test.

Thus, while in state 702, pressing the down key 20 causes the code tobranch to a decision at 830 as to whether the FLFI Test has already beenperformed, i.e., whether the FLFI Test Complete Flag is set. If the downkey 20 is pressed while the FLFI Test Complete Flag is not set, the coderemains in state 702 and waits for the user to press the star key 18,which will cause the code to branch to the beginning of the FLFI Test,via branch 704. If the down key 20 is pressed while the FLFI TestComplete Flag is set, the code branches at 832 to state 732, discussedabove, in which the results of the FLFI Test are displayed. Thus, fromstate 702, the user may back up to the previous step (state 690) bypressing the up key 19 and, if the FLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 720, which is the start of the FLFI Test, pressing the upkey 19 causes the code to branch at 834 to state 702, discussed above,in which the results of the NLFI Test are presented. While in state 720,if the FLFI Test has already been performed, i.e., if the FLFI TestComplete Flag is set, e.g., at task 728, the display conveys to the userthat the down key 20 is active, e.g., by displaying an imagecorresponding to that key, such as an image of a downwardly pointingarrow (e.g., down arrow 1004 in the screen shots in FIG. 13). While instate 720, pressing the down key 20 causes the code to branch to adecision at 840 as to whether the FLFI Test has already been performed,i.e., whether the FLFI Test Complete Flag is set. If the down key 20 ispressed while the FLFI Test Complete Flag is not set, the code remainsin state 720 and waits for the user to press the star key 18, which willcause the code to take a measurement of battery voltage, via branch 722.If the down key 20 is pressed while the FLFI Test Complete Flag is set,the code branches at 842 to state 732, discussed above, in which theresults of the FLFI Test are displayed. Thus, from state 720, the usermay back up to the previous test step (the end of the NLFI Test) bypressing the up key 19 and, if the FLFI Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 732, in which the results of the FLFI Test are presentedto the user, pressing the up key 19 causes the code to branch at 844 tostate 720, discussed above, in which the user is prompted to adjust thevehicle into the FLFI condition. While in state 732, if the Diode RippleTest has already been performed, i.e., if the Diode Ripple Test CompleteFlag is set, e.g., at task 758, the display conveys to the user that thedown key 20 is active, e.g., by displaying an image corresponding tothat key, such as an image of a downwardly pointing arrow. Screen 1018of FIG. 13 shows a display of the results of a hypothetical FLFI Testbefore the Diode Ripple Test has been performed, i.e., with the DiodeRipple Test Complete Flag cleared. Screen 1020 of FIG. 13 shows adisplay of the same FLFI Test results, with the Diode Ripple TestComplete Flag set, i.e., after the Diode Ripple Test has been performedat least once since the tester 10 was last powered up. Note the presenceof down arrow 1004 in screen 1020 that is not in screen 1018, indicatingthat the down arrow key is active and may be used to skip to the resultsof the Diode Ripple Test.

Thus, while in state 732, pressing the down key 20 causes the code tobranch to a decision at 850 as to whether the Diode Ripple Test hasalready been performed, i.e., whether the Diode Ripple Test CompleteFlag is set. If the down key 20 is pressed while the Diode Ripple TestComplete Flag is not set, the code remains in state 732 and waits forthe user to press the star key 18, which will cause the code to branchto the beginning of the Diode Ripple Test, via branch 734. If the downkey 20 is pressed while the Diode Ripple Test Complete Flag is set, thecode branches at 852 to state 762, discussed above, in which the resultsof the Diode Ripple Test are displayed. Thus, from state 732, the usermay back up to the previous step (state 720) by pressing the up key 19and, if the Diode Ripple Test has already been performed, the user mayredo that test by pressing the star key 18, or may skip the test(thereby retaining the data and results from the previous execution ofthat test) by pressing the down key 20.

While in state 750, which is the start of the Diode Ripple Test,pressing the up key 19 causes the code to branch at 854 to state 732,discussed above, in which the results of the FLFI Test are presented.While in state 750, if the Diode Ripple Test has already been performed,i.e., if the Diode Ripple Test Complete Flag is set, e.g., at task 758,the display conveys to the user that the down key 20 is active, e.g., bydisplaying an image corresponding to that key, such as an image of adownwardly pointing arrow (e.g., down arrow 1004 in the screen shots inFIG. 13). While in state 750, pressing the down key 20 causes the codeto branch to a decision at 860 as to whether the Diode Ripple Test hasalready been performed, i.e., whether the Diode Ripple Test CompleteFlag is set. If the down key 20 is pressed while the Diode Ripple TestComplete Flag is not set, the code remains in state 750 and waits forthe user to press the star key 18, which will cause the code to take ameasurement of battery voltage, via branch 752. If the down key 20 ispressed while the Diode Ripple Test Complete Flag is set, the codebranches at 862 to state 762, discussed above, in which the results ofthe Diode Ripple Test are displayed. Thus, from state 750, the user mayback up to the previous test step (the end of the FLFI Test) by pressingthe up key 19 and, if the Diode Ripple Test has already been performed,the user may redo that test by pressing the star key 18, or may skip thetest (thereby retaining the data and results from the previous executionof that test) by pressing the down key 20.

While in state 762, in which the results of the Diode Ripple Test arepresented to the user, pressing the up key 19 causes the code to branchat 864 to state 750, discussed above, in which the user is prompted toadjust the vehicle into the Diode Ripple condition. While in state 762,the display conveys to the user that the down key 20 is active, e.g., bydisplaying an image corresponding to that key, such as an image of adownwardly pointing arrow. Screen 1022 of FIG. 13 shows a display of theresults of a hypothetical Diode Ripple Test. Note the presence of downarrow 1004 in screen 1022, indicating that the down arrow key is activeand may be used to skip to the last state 770. Thus, while in state 762,pressing the down key 20 causes the code to branch via branch 866 tostate 770. Thus, from state 762, the user may back up to the previousstep (state 750) by pressing the up key 19 and advance to the next step(state 770) by either pressing the star key 18 or by pressing the downkey 20.

While in state 770, which is All Tests Complete state, pressing the upkey 19 causes the code to branch at 868 back to state 762, discussedabove, in which the results of the Diode Ripple Test are presented. Thisscreen is shown as screen 1024 in FIG. 13.

Therefore, while in state 770, after all of the tests have beenperformed, it takes twelve (12) presses of the up key 19 to move fromstate 770 back up to the beginning at state 602 (state 770 back to state762 back to state 750 back to state 732 back to state 720 back to state702 back to state 690 back to state 676 back to state 662 back to state624 back to either state 634 or state 606 back to state 602) and takesseven (7) presses of the down key 20 to move back down from state 602 tostate 770 (state 602 down to state 624 down to state 676 down to state702 down to state 732 down to state 762 down to state 770). This userinterface of the present invention greatly facilitates the userreviewing results of and redoing, if necessary, previously performedtests with the tester 10. In the alternative, the tester 10 can be codedso that while in state 770, after all of the tests have been performed,it takes twelve (12) presses of the up key 19 to move from state 770back up to the beginning at state 602, and takes twelve (12) presses ofthe down key 20 to move from state 602 back down to state 770.

The Starter Test was previously discussed in the context of task 522 inFIG. 10 and tasks 602-624 in FIGS. 11A-11B. Referring now to FIG. 12,additional information about the Starter Test is provided, focusing moreon the preferred testing method and less on the user interface than theprevious discussions. The Starter Test begins at task 900 in FIG. 12.The Starter Test routine first prompts the user at 902 to turn theengine off and to press the star key 18 when that has been done. Theuser pressing the star key 18 causes the code to branch at 904 to thenext task 906, in which the base battery voltage V_(b) is measured usingthe voltmeter circuit 100. Additionally, a crank threshold voltageV_(ref) is calculated by subtracting a fixed value from the base voltageV_(b), e.g., V_(ref)=V_(b)−0.5 VDC. In the alternative, the crankthreshold voltage V_(ref) can be determined by performing anothermathematical operation with respect to the base voltage V_(b), e.g.,taking a fixed percentage of the base voltage V_(b). In any event, avalue corresponding to the threshold voltage V_(ref) is transferred fromthe processor 42 to the DAC 80 via bus 81 to cause the DAC 80 to outputthe threshold voltage V_(ref) at output 83 b as one input to comparator82 b. In this state, after the voltage at output 83 b stabilizes, thecomparator 82 b constantly monitors the battery voltage, waiting for thebattery voltage to drop to less than (or less than or equal to) thethreshold level V_(ref).

Next, at step 908, the user is prompted to either start the engine ofthe vehicle under test or press the star key 18 to abort the startertest. Next, via branch 910, the code enters a loop in which theprocessor 42 periodically polls the input corresponding to comparator 82b to determine if the battery voltage has dropped to less than (or lessthan or equal to) the threshold level V_(ref) and periodically polls theinputs corresponding to switches 18-21 to determine if any key has beenpressed. Thus, at decision 912, if the output 85 b of comparator 82 bremains in a HIGH state, the processor tests at 914 whether any key hasbeen pressed. If not, the processor 42 again tests the comparator todetermine whether the comparator has detected a battery voltage drop,and so on. If at test 914 a key press has been detected, the message“Crank Not Detected” is displayed at 916 and the routine ends at 918.

On the other hand, at decision 912, if the processor 42 determines thatthe output 85 b of comparator 82 b has transitioned from a HIGH state toa LOW state, then the battery voltage has dropped to less than thethreshold level V_(ref) and the processor branches via 920 to code at922 that waits a predetermined period of time, preferably between about10 milliseconds and about 60 milliseconds, more preferably about 40milliseconds, and most preferably 40 milliseconds, before beginning tosample the battery voltage, i.e., the cranking voltage. Waiting thisperiod of time permits the starter motor to stabilize so that themeasured voltage is a stable cranking voltage and not a transientvoltage as the starter motor begins to function. Additionally, the codeat 922 also sets a variable N to 1 and preferably displays a message tothe user via display 24, e.g., “Testing.” The variable N is used totrack the number of samples of cranking voltage that have been taken.

Next at 924 the cranking volts V_(c) are measured using voltmeter 100and the measured cranking voltage is stored by processor 42 as V_(c)(N).Then the most recently measured cranking voltage sample V_(c)(N) iscompared to the value corresponding to the threshold voltage V_(ref)that was previously used at step 912 to determine the start of thecranking cycle, at 926. On the one hand, if at 926 the battery voltageis still less than V_(ref), then it is safe to assume that the startermotor is still cranking and the measurement V_(c)(N) represents acranking voltage. Accordingly, the processor next at 928 determines ifeight (8) samples have been taken. If so, the code branches at 930 totask 932. If not, then N is incremented at 934 and another crankingvoltage sample is taken and stored at 924 and the loop iterates.

On the other hand, if at 926 the battery voltage has risen to the extentthat it is greater than V_(ref), then it is safe to assume that the carhas started and it is meaningless to continue to measure and storebattery voltage, because the battery voltage samples no longer representa cranking voltage. Accordingly, the processor next at 936 tests todetermine if only one sample has been collected. If so, then the codebranches to task 932. If not, then the processor 42 has taken more thanone measurement of battery voltage and one voltage may be discarded bydecrementing N at 938 under the assumption that the Nth sample wasmeasured after the car had started (and thus does not represent acranking voltage), and the code continues to task 932.

At 932, the N collected cranking voltages are averaged to determine anaverage cranking voltage V_(c) ^(avg). At this stage, the rest of FIG.12 is essentially like that shown in FIG. 11A, except that a table ofthreshold values is set forth in FIG. 12. If the average crankingvoltage V_(c) ^(avg) is greater than 9.6 VDC, then the cranking voltageis deemed to be “OK” no matter what the temperature is, and the codebranches at 946, displays a corresponding message at 948, and ends at950. On the other hand, if the average cranking voltage V_(c) ^(avg) isless than 8.5 VDC, then the battery voltage during starting (“crankingvoltage”) is deemed to be “Low” no matter what the temperature is, i.e.,there might be problems with the starter, and the code branches at 940,displays a corresponding message at 942, and ends at 944. Finally, ifthe average cranking voltage is between 8.5 VDC and 9.6 VDC, then theprocessor 42 needs temperature information to make a determination as tothe starter. Accordingly, the processor 42 at step 952 prompts the userwith respect to the temperature of the battery with a message viadisplay 24 such as, “Temperature above xx°?” where xx is a thresholdtemperature corresponding to the average measured cranking voltage fromthe table 954 in FIG. 12. For example, if the average cranking voltageV_(c) ^(avg) is between 9.1 VDC and 9.3 VDC, the user is preferablyprompted to enter whether the battery temperature is above 30° F.Similarly, if the average cranking voltage V_(c) ^(avg) is between 9.3VDC and 9.4 VDC, the user is preferably prompted to enter whether thebattery temperature is above 40° F. In the alternative, the processor 42can interpolate between the various temperatures in the table in 954.For example, if the average cranking voltage V_(c) ^(avg) is 9.2 VDC,the user can be prompted to enter whether the battery temperature isabove 35° F. and if the average cranking voltage V_(c) ^(avg) is 9.35VDC, the user can be prompted to enter whether the battery temperatureis above 45° F. On the one hand, if the user indicates that the batterytemperature is greater than the threshold temperature, then the codebranches at 956, displays a corresponding message at 942, and ends at944. On the other hand, if the user indicates that the batterytemperature is less than the threshold temperature, then the codebranches at 958, displays a corresponding message at 948, and ends at950.

While the present invention has been illustrated by the description ofembodiments thereof, and while the embodiments have been described insome detail, it is not the intention of the applicant to restrict or inany way limit the scope of the appended claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. For example, the housing connector J1 can bereplaced with a number of discrete connections, e.g., a number ofso-called “banana plug” receptors, preferably with at least one of thediscrete connections providing a signal to the detection circuitry.Therefore, the invention in its broader aspects is not limited to thespecific details, representative apparatus and methods, and illustrativeexamples shown and described. Accordingly, departures may be made fromsuch details without departing from the spirit or scope of theapplicant's general inventive concept.

What is claimed is:
 1. A hand-held, portable battery tester for testinga battery via connecting to battery terminals of the battery,comprising: a. an electronic battery test circuit, said test circuitperforming at least one test on the battery; b. a hand-held, portableenclosure housing said electronic test circuit; c. a housing connectorproviding a plurality of electrical connections, said housing connectorbeing associated with said housing and said plurality of electricalconnections being in circuit communication with said electronic testcircuit; and d. a removable test cable for removably placing saidelectronic test circuit in circuit communication with the battery, saidtest cable: i. providing a plurality of electrical conductors; ii.having a removable cable connector at one end of conductors of saidplurality of electrical conductors for connection to said housingconnector to place conductors of said plurality of electrical conductorsin circuit communication with connections of said plurality ofelectrical connections; and iii. having a plurality of battery clips atother ends of conductors of said plurality of electrical conductors forconnection to the battery terminals; and wherein said removable cableconnector, said plurality of electrical conductors, and said pluralityof battery clips cooperate to provide a Kelvin connection from saidelectronic battery test circuit to the battery when said removable cableconnector is connected to said housing connector and said battery clipsare connected to the battery terminals.
 2. The hand-held, portablebattery tester according to claim 1, wherein said electronic testcircuit is further characterized by performing at least one other testin addition to testing the battery via connecting to the batteryterminals, the at least one other test being a test of an electronicdevice and the at least one other test using a different removable testcable connected to said housing connector for removably placing saidelectronic test circuit in circuit communication with the electricaldevice being tested.
 3. The hand-held, portable tester according toclaim 2, further comprising a plurality of removable test cables eachhaving a removable cable connector for selectively placing the testcircuit in circuit communication with the device being tested.
 4. Thehand-held, portable tester according to claim 3, wherein the pluralityof removable test cables comprise at least two removable test cables ofdifferent lengths.
 5. The hand-held, portable tester according to claim4, wherein the two removable test cables of different lengths cooperatein providing the Kelvin-type connection when connected to the terminalsof the battery.
 6. The hand-held, portable tester according to claim 3,wherein the plurality of removable test cables are selected from one ofa starter/charger test cable, a sensor cable, a probe cable and anextension cable.
 7. The hand-held, portable tester according to claim 6,wherein the sensor cable comprises a hall effect sensor.
 8. Thehand-held, portable tester according to claim 3, wherein the removabletest cable selected from the plurality of removable test cables includesa first removable test cable and a second removable test cable, whereinthe first removable test cable is configured to connect to the secondremovable test cable thereby extending the overall distance thehand-held portable tester can be used from the electrical device.
 9. Thehand-held, portable tester according to claim 2, further comprising testcircuitry to automatically detect whether the type of removable testcable connected to the hand-held portable tester is starter/charger testcable, a sensor cable, a probe cable or an extension cable.
 10. Ahand-held, portable battery tester for testing a battery via connectingto battery terminals of the battery, comprising: a. an electronicbattery test circuit, said test circuit performing at least one test onthe battery by applying an AC load current to the battery and analyzinga voltage generated by the load current applied to the battery; b. ahand-held, portable enclosure housing said electronic test circuit; c. ahousing connector providing a plurality of electrical connections, saidhousing connector being associated with said housing and said pluralityof electrical connections being in circuit communication with saidelectronic test circuit; and d. a removable test cable for removablyplacing said electronic test circuit in circuit communication with thebattery, said test cable: i. providing a plurality of electricalconductors; ii. having a removable cable connector at one end ofconductors of said plurality of electrical conductors for connection tosaid housing connector to place conductors of said plurality ofelectrical conductors in circuit communication with connections of saidplurality of electrical connections; and iii. having a plurality ofbattery clips at other ends of conductors of said plurality ofelectrical conductors for connection to the battery terminals; andwherein said removable cable connector, said plurality of electricalconductors, and said plurality of battery clips cooperate to provide aKelvin connection from said electronic battery test circuit to thebattery, to pass the AC load current through the battery via the batteryterminals and to communicate voltage generated across the batteryterminals by the AC load current back to the electronic battery testcircuit, when said removable cable connector is connected to saidhousing connector and said battery clips are connected to the batteryterminals.
 11. The hand-held, portable battery tester according to claim10, wherein said electronic test circuit is further characterized byperforming at least one other test in addition to testing the batteryvia connecting to the battery terminals, the at least one other testbeing a test of an electronic device and the at least one other testusing a different removable test cable connected to said housingconnector for removably placing said electronic test circuit in circuitcommunication with the electrical device being tested.
 12. Thehand-held, portable tester according to claim 11, further comprising aplurality of removable test cables each having a removable cableconnector for selectively placing the test circuit in circuitcommunication with the device being tested.
 13. The hand-held, portabletester according to claim 12, wherein the plurality of removable testcables comprise at least two removable test cables of different lengths.14. The hand-held, portable tester according to claim 12, wherein thetwo removable test cables of different lengths cooperate in providingthe Kelvin-type connection when connected to the terminals of thebattery.
 15. The hand-held, portable tester according to claim 12,wherein the plurality of removable test cables are selected from one ofa starter/charger test cable, a sensor cable, a probe cable and anextension cable.
 16. The hand-held, portable tester according to claim15, wherein the sensor cable comprises a hall effect sensor.
 17. Thehand-held, portable tester according to claim 12, wherein the removabletest cable selected from the plurality of removable test cables includesa first removable test cable and a second removable test cable, whereinthe first removable test cable is configured to connect to the secondremovable test cable thereby extending the overall distance thehand-held portable tester can be used from the electrical device. 18.The hand-held, portable tester according to claim 11, further comprisingtest circuitry to automatically detect whether the type of removabletest cable connected to the hand-held portable tester is starter/chargertest cable, a sensor cable, a probe cable or an extension cable.
 19. Ahand-held, portable tester for testing a starter/charger system of aninternal combustion engine via connecting to battery terminals of abattery of the starter/charger system, comprising: a. an electronic testcircuit, said test circuit capable of performing at least one test onthe starting/charging system via connecting to the battery terminals; b.a hand-held, portable enclosure housing said electronic test circuit;and c. a housing connector providing a plurality of electricalconnections, said housing connector being associated with said housingand said plurality of electrical connections being in circuitcommunication with said electronic test circuit; and d. a removable testcable for removably placing said electronic test circuit in circuitcommunication with the battery, said test cable: i. providing aplurality of electrical conductors; ii. having a removable cableconnector at one end of conductors of said plurality of electricalconductors for connection to said housing connector to place conductorsof said plurality of electrical conductors in circuit communication withconnections of said plurality of electrical connections; and iii. havinga plurality of battery clips at other ends of conductors of saidplurality of electrical conductors for connection to the batteryterminals; and wherein said removable cable connector, said plurality ofelectrical conductors, and said plurality of battery clips cooperate toprovide a Kelvin connection from said electronic battery test circuit tothe battery when said removable cable connector is connected to saidhousing connector and said battery clips are connected to the batteryterminals.
 20. The hand-held, portable tester according to claim 19,wherein said electronic test circuit is further characterized byperforming a plurality of tests on the starting/charging system viaconnecting to the battery terminals.
 21. The hand-held, portable testeraccording to claim 19, wherein said electronic test circuit is furthercharacterized by performing at least one test on a starting unit of thestarting/charging system via connecting to the battery terminals; andperforming a plurality of tests on a charging unit of thestarting/charging system via connecting to the battery terminals, atleast one of said tests on the charging unit of the starting/chargingsystem being a diode ripple test.
 22. The hand-held, portable testeraccording to claim 19, wherein said electronic test circuit is furthercharacterized by performing at least one test on a starting unit of thestarting/charging system via connecting to the battery terminals; andperforming at least four tests on a charging unit of thestarting/charging system via connecting to the battery terminals, atleast one of said tests on the charging unit of the starting/chargingsystem being a diode ripple test.
 23. The hand-held, portable testeraccording to claim 19, wherein said electronic test circuit is furthercharacterized by performing a plurality of tests on thestarting/charging system via connecting to the battery terminals,including performing at least one test on a battery of thestarting/charging system via connecting to the battery terminals. 24.The hand-held, portable tester according to claim 19, wherein saidelectronic test circuit is further characterized by performing at leastone test on a starting unit of the starting/charging system viaconnecting to the battery terminals; performing at least one test on abattery of the starting/charging system via connecting to the batteryterminals; and performing a plurality of tests on a charging unit of thestarting/charging system via connecting to the battery terminals, atleast one of said tests on the charging unit of the starting/chargingsystem being a diode ripple test.
 25. The hand-held, portable testeraccording to claim 19, wherein said electronic test circuit is furthercharacterized by performing at least one test on a starting unit of thestarting/charging system via connecting to the battery terminals;performing at least one test on a battery of the starting/chargingsystem via connecting to the battery terminals; and performing at leastfour tests on a charging unit of the starting/charging system viaconnecting to the battery terminals, at least one of said tests on thecharging unit of the starting/charging system being a diode ripple test.26. The hand-held, portable tester according to claim 19, wherein saidelectronic test circuit is further characterized by performing at leastone other test in addition to the at least one test on thestarting/charging system via connecting to the battery terminals, the atleast one other test being a test of an electronic device and the atleast one other test using a different removable test cable connected tosaid housing connector for removably placing said electronic testcircuit in circuit communication with the electrical device beingtested.
 27. The hand-held, portable tester according to claim 26,further comprising a plurality of removable test cables each having aremovable cable connector for selectively placing the portable tester incircuit communication with the device being tested.
 28. The hand-held,portable tester according to claim 27, wherein the plurality ofremovable test cables are selected from one of a starter/charger testcable, a sensor cable, a probe cable and an extension cable.
 29. Thehand-held, portable tester according to claim 28, wherein the sensorcable comprises a hall effect sensor.
 30. The hand-held, portable testeraccording to claim 27, wherein the removable test cable selected fromthe plurality of removable test cables includes a first removable testcable and a second removable test cable, wherein the first removabletest cable is configured to connect to the second removable test cablethereby extending the overall distance the hand-held portable tester canbe used from the electrical device.
 31. The hand-held, portable testeraccording to claim 26, further comprising test circuitry toautomatically detect whether the type of removable test cable connectedto the hand-held portable tester is starter/charger test cable, a sensorcable, a probe cable or an extension cable.
 32. The hand-held, portabletester according to claim 19, further comprising a plurality ofremovable test cables each having a removable cable connector forselectively placing the test circuit in circuit communication with thedevice being tested.
 33. The hand-held, portable tester according toclaim 19, wherein the plurality of removable test cables comprise atleast two removable test cables of different lengths.
 34. The hand-held,portable tester according to claim 19, wherein the two removable testcables of different lengths cooperate in providing the Kelvin-typeconnection when connected to the terminals of the battery.